P4 Flashcards
(97 cards)
1
Q
what are the 3 particles in an atom?
A
protons, neutron and electrons
2
Q
where are protons, neutrons and electrons found?
A
protons & neutron: in the nucleus
electrons: in the shells
3
Q
what happens when 2 of the same charged particles experience a force?
A
they repell
4
Q
what happens when 2 of opposite charged particles experience a force?
A
they attract
5
Q
what is the relative charge of a proton?
A
positive +1
6
Q
what is the relative mass of a proton?
A
1
7
Q
what is the relative charge of a neutron?
A
neutral, 0
8
Q
what is the relative mass of a neutron?
A
1
9
Q
what is the relative charge of an electron?
A
negative, -1
10
Q
what is the relative mass of an electron?
A
1/2000th
11
Q
what is the charge of an atom? why?
A
they are neutrally charged
-bcus their no. of protons = no. of electrons
12
Q
what is the overall charge of the nucleus?
A
positive
13
Q
equation: relative mass of an atom
A
protons+ neutron
14
Q
what is the atomic number?
A
number of protons
15
Q
what is the mass number?
A
protons + neutrons
16
Q
what are isotopes?
A
atoms with the same number of protons but different number neutron
17
Q
what is ionisation?
A
the process in which an atom becomes an ion
18
Q
what is excitation?
A
when energy is provided by light and en electron goes to a higher energy level
19
Q
n.d what is relaxation?
A
20
Q
what are 2 reasons for ionisation? Check
A
- another electron rushes past the atom with lots of energy and collides, with the atom and gives some of its energy within the atom and the electron has enough energy to escape
2, light of enough energy strikes the atom (e.g ultraviolet light)
21
Q
what did Democritus come up with in 400BC?
A
everything is composed of atoms
22
Q
what did John Dalton come up with? in what year?
A
- all matter is composed of atoms
- atoms can’t be subdivided or destroyed
- 1803
23
Q
what did JJ Thompson come up with? what year?
A
The Plum Pudding Model
- 1904
24
Q
what 3 things does the plum pudding model consist of?
A
- a positive ‘blob’
- negatively charged electrons scattered inside
- removing an electron made an ion
25
give 3 characteristics of Alpha particles
1. positively charged
2. light weight
3. fast
26
what happens to the Fluorescent screen when alpha particles hit it?
it glows
27
Give 3 results of the alpha particles experiment
1. most of the alpha particles passed straight through
2. some would be deflected/ change direction
3. a few would bounce back
28
what did it mean when most of the alpha particles went straight through?
means atoms are mostly empty space
29
What did it mean when some of the alpha particles deflected/ changed direction?
it meant the centre of the atoms are positively charged
30
what did it mean when a few alpha particles bounced straight back?
the centre of the atom is very small and dense, with a positive charge
31
what charge do alpha particles have?
positive
32
what charge does a gold atom have?
no charge, it's neutral
33
what is the plum pudding model.
a ball of positive charge with negative electrons randomly embedded
34
what are 2 main changes to the atomic model the alpha scattering experiment resulted in?
mass: concentrated in the centre
charge: positive charge at the centre
35
who discovered the 1st chemical element?
Marie Curie
36
What did Marie Curie name the first chemical element?
Polonium
- after Poland
37
When does Radioactivity occur?
when the nucleus of an atom is unstable
38
what are the 4 types of nuclear radiation?
- order they were discovered
Alpha
Beta
Gamma
Neutron
39
what is alpha radiation made from?
2 protons and 2 neutrons
- comes out the nucleus very fast --> has lots of energy
40
What is beta radiation?
a high speed electron from the nucleus of an atom
41
what is gamma radiation? (5)
are waves of electromagnetic radiation from the nucleus
- high energy
- are a family of radiation
- don't have mass
- not real particles
42
penetrating meaning?
able to make a way through or into something.
43
describe the penetrating power of an alpha radiation? what is it stopped by?
low penetrating power
- stopped by small/thin stuff (e.g piece of paper)
44
describe the penetrating power of beta radiation? what is it stopped by?
medium penetrating power
- stopped by a few mm of aluminium, copper, steel
45
describe the penetrating power of gamma radiation? what is it stopped by?
high penetrating power
- blocked by thick lead or concrete
46
what would a strong gamma radiation require for it to penetrate?
thicker lead or concrete
47
describe alpha radiation's range in air?
few cm (1-4cm)
- can be measure with ruler
- has large particles so only travel few cm before alpha particles collide with air molecules and give up their energy
48
describe beta radiation's range in air?
range is long (1-2 metres)
- measure with tape metre
- travel few metre before beta particles collide with airmolecules
49
why is alpha radiation and beta radiation range in air lower?
because their particles collide with air molecules
and give up their energy
50
describe gamma radiation's range in air?
long range
(10- billions of kilometres)
51
describe the ionising power of alpha radiation
has a high ionising power
- because has a charge of +2
52
describe the ionising power of beta radiation
medium ionising power
- because has a charge of -1
53
describe the ionising power of gamma radiation
has a low ionising power
- because has a neutral charge
54
what does more charge or more energy mean in terms of ionising power?
higher ionising power
55
Alpha radiation (3)
(Penetrating/ionising power, range in air rank)
1. least penetrating power
2. most ionising power
3. least range in air
56
beta radiation (3)
- 2nd most penetrating power
- 2nd most ionising power
- 2nd longest range in the air
57
gamma radiation (3)
1. most penetrating power
2. least ionising power
3. greatest range in the air
58
when are alpha, beta, gamma radiation the most hazardous?
alpha: in short range
beta: in mid- range
gamma: in long range
59
what is a gamma ray?
a type of electromagnetic radiation
60
what is the best absorber of a gamma ray?
a thick sheet of lead
61
what is the best absorber of beta radiation?
aluminium, copper or steel
62
how many isotopes does iodine have?
37
63
when is it decayed by alpha decay?
when the nuclei is too large (larger than lead)
64
when is it decayed by beta decay?
when the nuclei has too many neutrons
65
what happens to the mass number in alpha decay?
drops by 4
66
what happens to the atomic number (proton number) in alpha decay?
drops by 2
67
what happens to the mass number in beta decay?
stays the same
68
what happens to the atomic number in beta decay?
increases by 1
69
what is the atomic mass number of the emitted alpha particle?
4
70
what is the number of protons in an alpha particle?
2
71
what is the number of neutrons in an alpha particle?
2
72
what is the atomic mass number emitted beta particle?
0
73
what is meant by half life?
the time taken for half of the unstable nuclei to decay
74
what does an unstable nuclei do to become stable?
emits radiation
75
Can you predict radioactive decay? why?
No because it is random, spontaneous and unpredictable
76
what is activity measured in?
becquerel (Bq)
77
what is activity?
the rate at which a source of unstable nuclei decay
78
what is contamination?
when an object/body contains a small amount of a radioactive isotope
79
what is irradiation?
when an object or body is exposed to nuclear radiation
80
when is it irradiation?
when it is alpha, beta, gamma radiation
81
when is it contamination?
when it is an isotope or an element
82
how to protect against contamination?
control the isotope
- wear gloves
- breathing apparatus
83
how to protect against irradiation? (4)
block the radiation
- lead/ concrete shields
-badges to monitor the dose
- limit exposure time
- keep your distance
84
how are alpha particles used for smoke detectors?
when smoke gets into the detectors the alpha particles are blocked ---> so ionisation can no longer take place ---> signal is sent to alarm
85
how are beta particles used to make paper?
too much beta particles means the paper is too thin so sends message to computer
86
how are gamma particles used in food production?
ionise DNA within bacteria and fungi --> stops them from reproducing (on food)
87
what are 3 hazards of ionising radiation?
1. can damage DNA
2. kills cells and (3) destroys tissues
88
what does contamination do?
transfers the source
89
Irradiation is...
is emission from the source
90
which has a higher level of risk contamination or irradiation?
contamination
91
which lasts longer contamination or irradiation?
contamination
- irradiation is temporary
92
n.d What did Rutherford come up with?
93
n.d what did Bohr come up with in 1919?
94
is beta radiation an electron?
It's not actually an electron , it is a particle that is identical to an electron but comes from the nucleus.
95
where does beta radiation (particle) come from?
the nucleus
96
what is neutral radiation?
neutron
97
